In the natural world, the color red doesn’t get much better thanwith the Red Rainbowfish!

Like so many fish, the Red Rainbowfish Glossolepis incisus is known by variety of other names. Yet in almost all its designations you can’t help but to notice the predominant phrase ‘red’. Some of its common names are Salmon Red Rainbowfish, Red Irian Rainbowfish, and New Guinea Red Rainbowfish. By these names, there is no misunderstanding of the impression this striking fish makes. This species quickly and uniquely demonstrates the appeal of the rainbowfish family.

The Red Rainbowfish is one of the larger rainbow fish species, reaching almost 6 inches (15 cm) in size. It is a peaceful fish and can be kept with other similar sized and like tempered tank mates. However it needs to be kept in a school of 6 or more of its own kind to do its best and bring out the vibrant reds in adult males. Consequently it needs a very large tank of 150 gallons (568 l) or more with lots of plants and bog wood type decor. It needs plants for cover and security, yet needs lots of open space to swim.

When the Salmon Red Rainbowfish is kept in a mixed school of male and female fish, you will see a constantly changing show of crimson and silver in the male. The color of the female is less inspiring, but without a female to display to the males will be a dull dusty brown. It is competition between males that brings out the best colors. To see good strong reds, frequent water changes are also essential. This is a most excellent fish for any aquarist willing to accept the challenge.

The Red Rainbowfish is currently listed as vulnerable, and may become endangered in the near future. This is due to over harvesting and being very sensitive to the human population growth of this area. The purchase of wild caught specimens for direct sale or for irresponsible breeding has seriously impacted wild populations. In addition to dangers in the wild, this fish is often poorly bred, leading to a genetically weak captive population. Considering the precarious position this species is in, the aquarist should first consider buying carefully bred specimens rather than “farmed” or wild caught specimens.

For Information on keeping freshwater fish, see:
Freshwater Aquarium Guide: Aquarium Setup and Care

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Atheriniformes
  • Family: Melanotaeniidae
  • Genus: Glossolepis
  • Species: incisus
Red Rainbowfish – Quick Aquarium Care
  • Aquarist Experience Level: Beginner
  • Size of fish – inches: 6.0 inches (15.24 cm)
  • Minimum Tank Size: 35 gal (132 L)
  • Temperament: Peaceful
  • Aquarium Hardiness: Very Hardy
  • Temperature: 70.0 to 79.0° F (21.1 to 26.1&deg C)
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Habitat: Distribution / Background

The Red Rainbowfish Glossolepis incisus was described by Weber in 1907. It is found only in Lake Sentani and its tributary streams in the northeastern region of West Papua New Guinea (formerly Irian Jaya), near the city of Jayapura. Other common names it is know by are Salmon Red Rainbowfish, Red Irian Rainbowfish, and New Guinea Red Rainbowfish. It is also sometimes referred to as Lake Sentani Rainbowfish and Irian Jaya Rainbowfish,. However this is a bit confusing as both of these names are the primary common names for other species, Chilatherina sentaniensis and Melanotaenia irianjaya respectively.

The Red Rainbowfish is listed as Vulnerable (VU) on the IUCN Red List. This is because it is endemic to Lake Sentani and its connecting streams, and it is very sensitive to the human population growth of this area. As with all Rainbowfish, they are sensitive to water changes, and the introduction of humans in the area brings with it waste and other pollutants that get put into the waters.

Humans are also looking at using this lake as a fish farm where they would introduce and raise much larger fish that could eventually wipe out the entire population of Red Rainbowfish. This happened to the Lake Eacham Rainbowfish Melanotaenia eachamensis and there is concern it could happen to the Red Rainbowfish as well. Some of the exotic species introduced into these habitats include carp, tilapia, walking catfish, barbs, and gouramis.

Red Rainbowfish tend to gather around the margins of the lake where there is vegetation and bog type wood. The area they inhabit is fairly hilly so the streams tend to have very clear and rapidly moving currents. These fish feed on bugs that fall in the water as well as a variety of plant matter. Both the lake and streams they live in are on the alkaline side. This area is also warm, being close to the equator, so these fish should not be introduced to cold water tanks.

  • Scientific Name: Glossolepis incisus
  • Social Grouping: Groups – Congregates in groups, like other rainbow fishes.
  • IUCN Red List: VU – Vulnerable – Human population around the lake are causing a decline in this fish population.


The Red Rainbowfish is one of the larger rainbow fish species, reaching up to 6 inches (15 cm) in length. It is a long, slender fish, though mature males will have a highly arched back and very narrow head. Salmon Red Rainbowfish show many typical rainbow fish characteristics, namely large eyes, a deeply forked mouth and two dorsal fins. In the right setting, mature males have a brilliant blood red body and fin color. The body is accented with silver scales. Females and young males are generally a uniformly dull olive brown in color with clear gray fins.

It’s important to note that age, health, mood, water quality, temperature, and rank in the school will all impact the shade and intensity of red in the male displays. These factors can also impact the overall coloration of the females and non-dominant males. For example, in an aquarium kept at around 71.6° F (22° C) all the males will show red and the females will be a silvery color with yellow tinge. While if the water is kept too warm, only the strongest male will display the magnificent reds while the other males will be a reddish brown.

  • Size of fish – inches: 6.0 inches (15.24 cm) – Can reach 6″ (15cm), but are usually a bit smaller in the aquarium.
  • Lifespan: 6 years – Can have a life span up to 8 years in a well maintained aquarium.

Fish Keeping Difficulty

The Red Rainbowfish is actually a fairly easy fish to keep in an aquarium. These fish are a bit easier then many of the rainbowfish to get their colors to come out. Provide a good filtration system and use diligence with water changes.. With a school of 6 or more, the proper water conditions and temperature, and a high quality mix of foods, these fish will be active, show their best colors and thrive.

  • Aquarium Hardiness: Very Hardy
  • Aquarist Experience Level: Beginner

Foods and Feeding

Red Rainbowfish are omnivores that usually eat a heavily meat based diet of bugs and insects, along with a variety of plant matter in their natural habitat. They require a high quality diet to promote good coloration. Live and processed foods are both essential to its well being. Buy processed foods in small amounts and frequently, as the nutritional value of these products quickly deteriorates past usefulness. Specially prepared commercial foods that are sold as ‘color food’ will contain dyes like carotene which is advantageous to enhance their color.

Some good live food options include bloodworms, tubifex worms, water fleas, or brine shrimp. These should be fed at least twice per week as a supplement to the prepared diet. If these are unavailable live, frozen (defrosted) substitutes would also be accepted. Rainbow fish are one of the few fish that can digest ants, so these are always nice little treats for them. These fish should be fed 2 times a day and only what they can consume in less then 5 minutes.

  • Diet Type: Omnivore
  • Flake Food: Yes
  • Tablet / Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet – Suitable live food include bloodworms, tubifex worms, water fleas, or brine shrimp. The Red Rainbowfish are also one of the few fish that can digest ants, so those can also make an occasional treat.
  • Vegetable Food: Some of Diet
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day – Feed twice a day, but give them only what they can consume in less than 5 minutes.

Aquarium Care

Rainbowfish are not exceptionally difficult to care for provided their water is kept clean. At least 30 – 50% of the tank water should be replaced weekly, especially if the tank is densely stocked. If a constant regimen of weekly water changes is not upheld, expect poor coloration. Keeping the tank at a lower temperature of 71.6° F (22° C) will make more of the males display brighter red colors. When startled these fish may jump, so a tight aquarium hood will prevent them from getting airborne.

  • Water Changes: Weekly – Weekly water changes of 30 – 50%, depending on stocking density.

Aquarium Setup

The Red Rainbowfish is a large, active, high energy rainbow fish. Because they are very active swimmers the aquarium should be spacious, with 35 gallons being the absolute minimum. Eventually adults will need a much larger tank, with 150 gallons or more being reasonable. The tank should be securely covered as these fish are skilled jumpers and will jump when startled. A quality canister filter will be best to maintain suitable water conditions. Powerheads should be used to create water movement through dense vegetation.

These Red Irian Rainbowfish will do best and are most effectively displayed in tanks which simulate their natural habitat. A sandy substrate, dense vegetation, and bog wood all echo their native lake areas. As with most of the Rainbowfish species they are most at home in well planted aquariums. The tank should be planted in the sides and back, with a stretch of open water in the middle. The plants should be sturdy enough to stay rooted and recover from any browsing.

Using a good light with a good red spectrum will help bring out their colors. Also using rocks and driftwood as decoration will give a nice back drop to show off their colors.If you choose to add bog wood, take care that your water is hard enough that you don’t experience a pH drop. Slightly cooler temperatures, around 70° F (21° C) will make more of the males display brighter colors.

  • Minimum Tank Size: 35 gal (132 L) – A tank of 50 – 60 gallons or more is advisable for these large active swimmers, adults will need a much larger tank of 150 gallons.
  • Suitable for Nano Tank: No
  • Substrate Type: Sand/Gravel Mix
  • Lighting Needs: Moderate – normal lighting
  • Temperature: 70.0 to 79.0° F (21.1 to 26.1&deg C)
  • Breeding Temperature: 75.0° F – Breeding temperatures will be between 75 – 81° F ( 24 – 27° C)
  • Range ph: 6.5-8.5
  • Hardness Range: 8 – 25 dGH
  • Brackish: No
  • Water Movement: Moderate
  • Water Region: Top – Red Rainbowfish swim wherever there is open water, usually in the top or middle region.

Social Behaviors

Red Rainbowfish do fine in a community aquarium of similarly sized fish, but do exceptionally well in a geographical tank stocked with other rainbowfish. Although generally non-aggressive, overly aggressive or very shy tank mates will make bullies out of them. Mix them with other playful but good natured fish for best results. If in a tank with both other males and females, the males will occupy themselves by displaying their brightest and best red colors and flaring their fins. When males are displaying, you may notice some chasing between rainbowfish, but this is rarely a concern unless a fish is injured, has nowhere to hide, or is constantly harassed (usually a result of one of the first two).

Red Rainbowfish are schooling fish and the ratio of males to females is very important to keep a reasonable peace among them when numbers are small. Although you can always keep single sex schools, don’t expect to see any red coloration out of the males without representation from both genders. Properly stocking rainbow fish is a little tricky so we include the following recommendation for stocking. Choose which type of school you want to keep and how many fish.

If you wish to keep…

  • 5 rainbowfish – Do not mix sexes
  • 6 rainbowfish – 3 males + 3 females
  • 7 rainbowfish – 3 males + 4 females
  • 8 rainbowfish – 3 males + 5 females
  • 9 rainbowfish – 4 males + 5 females
  • 10 rainbowfish – 5 males + 5 females
  • Venomous: No
  • Temperament: Peaceful
  • Compatible with:
    • Same species – conspecifics: Yes – Groups of 6 or more are preferred.
    • Peaceful fish (): Safe – Similar size tank mates are best, as these largeractive rainbowfish can make smaller fish nervous.
    • Semi-Aggressive (): Monitor
    • Aggressive (): Threat
    • Large Semi-Aggressive (): Threat
    • Large Aggressive, Predatory (): Threat
    • Monitor – Rainbowfish are active fish that can make slower fish nervous and stressed.
    • Shrimps, Crabs, Snails: Safe – not aggressive
    • Plants: Safe – Plants need to be sturdy enough to stay rooted and recover from any browsing.

Sex: Sexual differences

Mature males will be much redder, have the arched back described above, and will often be the more territorial sex.

Breeding / Reproduction

A breeding tank should be set up with a sponge filer and either many fine leaved plants or a spawning mop. A pair of healthy adult rainbowfish should be introduced. They should be conditioned with live foods and plant based foods. Remember, you are trying to emulate the bounty of the flood season so feed more and higher quality food than you normally would.

After the female has produced eggs, the males will display an amazing show of intense colors and direct the female to the spawning site, spawn, and then rest. The spawning mop or plants should be removed and replaced after the spawning or the eggs will be eaten. The fish will repeat this daily for a few days, with steadily decreasing numbers of eggs produced. The parents should be removed when egg numbers fall or if the females show signs of fatigue.

The fry will hatch after about a week and should be fed infusoria or a liquid fry food until they are able to eat small live foods. The fry are something of a challenge to raise until they are about two months old. The fry grow slowly and require clean water during the entire process.

A problem to be aware of is crossbreeding. Rainbowfish in the wild will not breed with fish of another species, even when presented the opportunity to do so. But for some reason, rainbowfish of the Melanotaeniidae family in the aquarium will interbreed, often with undesirable results. Somehow the fry of mismatched parents lose most of their coloration. Since many of these species are rare, it is desirable to keep the bloodlines distinct, or risk losing the beautiful coloration that nature has taken thousands of years to develop. See an overview of how to breed Rainbow fish in Breeding Freshwater Fish.

  • Ease of Breeding: Moderate

Fish Diseases

Most Rainbows are prone to skin flukes, parasitic infestations (protozoa, worms, etc.), ichthyobodo infection, parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial disease. Goiters can be common in these fish in aquariums and normally caused from diet deficiencies, usually from not enough iodine.

Rainbowfish are generally hardy and disease is not usually a problem in a well maintained aquarium. That being said there is no guarantee that you won’t have to deal with health problems or disease. Remember anything you add to your tank can bring disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance.

A good thing about rainbow fish is that due to their resilience, an outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. When keeping more sensitive types of fish, it is common for all fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your Rainbow fish the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. Stressed fish are more likely to acquire disease.

For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments. This is a great source for information on disease and treatments. It is recommended to read up on the common tank diseases. Knowing the signs and catching and treating them early makes a huge difference. Rainbow fish are very resilient.


The Red Rainbowfish is also sold as Salmon Red Rainbowfish, Red Irian Rainbowfish, and New Guinea Red Rainbowfish. It is widely available in pet stores and online, and is moderately priced inline with most other rainbow fish species.


 Melanotaeniidae – Glossolepis incisus (Image Credit: Hectonichus, Wikimedia Commons CC BY-SA 3.0 Unported)